Determination of gas phase adsorption isotherms--a simple constant volume method

Single and ternary solute gas phase adsorption isotherms were conducted in this study to evaluate the effectiveness of a simple constant volume method, which was utilized by using Tedlar gas sampling bags as a constant volume batch reactor. For this purpose, gas phase adsorption of toluene, methyl ethyl ketone (MEK), and methyl isobutyl ketone (MIBK) on two types of activated carbons, BPL-bituminous base and OVC--coconut base, were investigated. For the single solute adsorption, the experimental adsorption data were found to be well correlated with Freundlich and Myers adsorption equations. The pore size distribution of adsorbents was found to affect their adsorption capacities; its effect was dependant on the solute concentration. The ternary adsorption experimental isotherms were accurately predicted by using the well-known model, i.e., ideal adsorbed solution theory (IAST).     

Toxicity and repellency of hot pepper extracts to spider mite, Tetranychus urticae Koch

Increasing concern about persistence and environmental impact of synthetic pesticide residues require development of biodegradable and environmentally safe alternatives. The potential of using fruit extracts of hot pepper as alternatives to synthetic acaricides for controlling the two-spotted spider mite, Tetranychus urticae Koch, is explored in this study. Twenty-four Capsicum accessions (Solanaceae) were screened for their toxicity and repellency to the spider mites. Crude extracts from fruits of C. chinense, C. frutescens, C. baccatum, C. annuum, and C. pubescens were prepared in methanol and tested for their acaricidal properties. Spider mite mortality was greatest (45%) when fruit extract of accession Grif-9169 (C. annuum) was used. Results from diving board bioassays indicated that mites avoided filter paper strips treated with hot pepper extracts from accessions PI-596057 (C. baccatum), PI-195299 (C. annuum), and Grif- 9270 (C. annuum). This investigation suggests that methanolic extracts of these three accessions may have a great potential for repelling spider mites and should be field-tested on a large-scale to assess their value in managing populations of spider mites, which could reduce reliance on synthetic acaricides. An attempt was made to correlate repellency with chemical constituents of fruit extracts of the most repellent accessions to identify chemical sources of repellency. Capsaicin and dihydrocapsaicin, the pungent components of pepper fruit, were not correlated with toxicity or repellency, indicating that these are not likely related to the toxicity or repellency of the pepper fruit extracts. Other, unidentified chemicals are likely responsible for toxicity and repellency to the two-spotted spider mite.     

Antioxidants in hot pepper: variation among accessions

The U.S. Department of Agriculture (USDA) pepper (Capsicum spp.) germplasm collection contains several thousand members or accessions. Many of these species and cultivars have not been analyzed for their concentrations of ascorbic acid, capsaicin, and total phenolic compounds, which are important antioxidants having a number of benefits for human health. The objective of this investigation was to select candidate accessions of hot pepper having high concentrations of ascorbic acid, capsaicin, free sugars, and total phenols for use as parents in breeding for these compounds. Seventeen accessions of pepper from the core Capsicum germplasm collection (four accessions of Capsicum chinense; five accessions of C. baccatum; six accessions of C. annuum; and two of C. frutescens) were field grown and their mature fruits were analyzed for their antioxidant composition. Concentrations of these compounds tended to be higher in C. chinense and C. baccatum, than in C. annuum and C. frutescens. Across all accessions the concentration of total phenols was correlated with ascorbic acid (r = 0.97) and free sugars (r = 0.80). Concentrations of total phenols (1.4, 1.3, and 1.3 mg g-1 fruit) and ascorbic acid (1.6, 1.2, and 1.3 mg g-1 fruit) were significantly greater in PI-633757, PI-387833, and PI-633754, respectively, compared to other accessions analyzed. Total capsaicinoids concentrations were greatest (1.3 mg g-1 fruit) in PI-438622 and lowest (0.002 mg g-1 fruit) in Grif-9320. The great variability within and among Capsicum species for these phytochemicals suggests that these selected accessions may be useful as parents in hybridization programs to produce fruits with value-added traits.     

Forest Restoration on a Closed Landfill: Rapid Addition of New Species by Bird Dispersal

Urban areas often contain sizeable pockets of degraded land, such as inactive landfills, that could be reclaimed as wildlife habitat and as connecting links to enhance remnant natural areas. In the northeastern U.S., many such lands fail to undergo natural succession to woodland, instead retaining a weedy, herbaceous cover for many years. We hypothesize that seed dispersal is a limiting factor, and that a form of secondary succession could be stimulated by introducing clusters of trees and shrubs to attract avian seed dispersers. As a direct test, we censused a 1.5-ha experimental plantation on the Fresh Kills Landfill (Staten Island, New York) one year after installation, in search of evidence that the plantation was spreading or increasing in diversity. The 17 planted species, many from coastal scrub forests native to this region, were surviving well but contributed almost no seedlings to the area, in part because only 20% of the installed trees or shrubs were reproductive. Of the 1079 woody seedlings found, 95% came from sources outside the plantation; most (71%) were from fleshy-fruited, bird-dispersed plants from nearby woodland fringes. Although the restoration planting itself had not begun to produce seedlings, it did function as a site for attracting dispersers, who enriched the young community with 20 new species. One-fourth of all new recruits were from nine additional wind-dispersed species. Locations with a high ratio of trees to shrubs had proportionately more recruits, indicating that plant size contributed to disperser attraction. The density of new recruits of each species was dependent on distance from the nearest potential seed source. Introducing native species with the capacity to attract avian dispersers may be the key to success of many restoration programs.     

Very low versus undetectable maternal serum alpha-fetoprotein values and fetal death

Very low maternal serum alpha-fetoprotein (MSAFP) levels (<10 ng/mL) are known to be associated with non-viable pregnancies, including conditions such as fetal death, molar pregnancies, and non-pregnancies. There has not been agreement, however, as to whether very low MSAFP levels indicate already existing fetal deaths or are actually predictive. We analysed 230 pregnancies with MSAFP levels <10 ng/mL from among 15 807 women (1.5 per cent) screened consecutively during a three-year period and identified 26 non-viable pregnancies, 22 of which were diagnosed sonographically as part of the screening process (17 missed abortions, 3 blighted ova, 2 non-pregnancies). Furthermore, 20 of these 22 pregnancies were associated with essentially undetectable MSAFP levels (<5 ng/mL). Our data indicate that pregnancies with MSAFP values <5 ng/mL are the group most strongly associated with fetal non-viability and that very low MSAFP values are not strongly predictive for fetal death.     

Modeling depth filtration of activated sludge effluent using a compressible medium filter.

A new filter, using a compressible-filter medium, has been evaluated for the filtration of secondary effluent. The ability to adjust the properties of the filter medium by altering the degree of the medium compression is a significant departure from conventional depth-filtration technology. Unlike conventional filters, it is possible to optimize the performance of the compressible-medium filter (CMF) by adjusting the medium properties (i.e., collector size, porosity, and depth) to respond to the variations in influent quality. Because existing filter models cannot be used to predict the performance of the CMF, a new predictive model has been developed to describe the filtration performance of the CMF and the effect of medium-compression ratio. The model accounts for the fact that the properties of the filter medium change with time and depth. The model, developed for heterodisperse suspensions and variable influent total suspended solids concentrations, can be used to predict all possible phases of filtration (i.e., ripening, constant removal, and breakthrough). A hyperbolic-type, second-order, nonlinear, partial-differential equation was derived to model the CMF. The equation was solved using the finite-difference numerical method. The accuracy of the numerical method was tested by a sensitivity analysis and a convergence test. The model is first-order accurate with respect to medium depth and time. Field data were obtained for the filtration of settled secondary effluent using a CMF with a capacity of 1200 m3/d. Model predictions were compared with observed performance from filter runs conducted at medium-compression ratios between 15 and 40% and filtration rates from 410 to 820 L/m2 min. The difference between the observed and the predicted values was found to be within 0 to 15%.     

Comparative assessment of municipal wastewater disposal methods in southeast Florida.

A comparative assessment of the risks of three effluent disposal alternatives currently available to wastewater utilities in Southeast Florida is presented in this paper. The alternatives are: deep well injection and ocean outfalls following secondary treatment, and surface water (canal) discharges following secondary wastewater treatment, filtration and nutrient removal. Water quality data, relative to disposal of wastewater treatment plant effluent were gathered, along with water quality data on the receiving waters, from utilities. Comparisons and conclusions regarding potential health concerns associated with the three disposal alternatives are presented. The results indicated that health risks associated with deep wells were generally lower than those of the other two alternatives. The proximity of injection wells to aquifer storage and recovery wells was a determining factor relative to injection well risk. Urban ecological risks were also indicated to be lower, though impacts of urban water use/reuse to the Everglades were not studied. Additional data collection and analysis were recommended to understand the effects of wastewater management on the cycling of water, nutrients and other constituents on southeast Florida. In particular, it was recommended that monitoring of effluents for nitrosamines and pharmaceutically active substances be implemented on a broad scale.